The present examples relate to multilayer optical discs and to an optical disc apparatus applicable to a multilayer optical disc.
Media families such as DVDs, Blu-ray discs, and HD DVDs, are known which has multilayer optical discs. These multilayer optical discs are two-layer discs defined by the relevant standards for current products. In the meantime, as described in “2006 Optical Data Storage Topical Meeting Conference Proceedings (pp 123-125, pp 185-187)”, for example, researches on four-layer and six-layer optical discs are underway.
Also, the techniques disclosed in JP-A-2004-62976 and JP-A-2005-332493 are known as the background art related to the present example. Methods of manufacturing a multilayer optical disc are described in these patent application publications. In addition, a multilayer optical information-recording medium that has preferable reproduction signal quality is described in JP-A-2007-004951.